(1) Field of the Invention
The present invention concerns an on-board MLS receiver circuit for decoding a fast-scanning boosted preamble.
(2) Description of the Invention
The French patent application No. 83 10 239 (published Jan. 18, 1985 and granted Apr. 1, 1986 as U.S. Pat. No. 2,549,321). describes an anti-clutter process for an MLS (Microwave Landing System) system wherein the revolving beam of the ground transmitter broadcasts an additional preamble for each function or group of functions, this additional preamble (called the "boosted preamble") being made up of pulse pairs used to identify the associated functions that follow them. This patent application also describes an on-board receiver that is capable of receiving, decoding and using a boosted preamble of this kind.
The decoder of this on-board receiver works well when there is no clutter, but is not protected against noise in general and against clutter pulses in particular.
The subject of the present invention is an on-board MLS receiver circuit to decode a fast-scanning boosted preamble, namely a decoding circuit that is efficiently screened against noise and clutter pulses insofar as the amplitude of these pulses is smaller than that of the pulses to be received or insofar as their shape is different.